Why is it called Halloween?

The word, once written as Hallowe’en but usually without the apostrophe these days, is a shortened form of All Hallows' Evening.

The word hallow comes from the Anglo-Saxon word for saint.

In the Christian calendar, it’s called All Hallows’ Eve and is the first day in a triduum (three-day religious festival) that continues with All Saints’ Day on November 1 and then All Souls’ Day on November 2.

The three-day festival is called Allhallowtide and is a time to remember the dead including saints and martyrs.

Why is it on that date?

The modern date of Halloween and the other two days appear to have been established by the Roman Catholic Church in the 9th century.

Before that, All Saints’ Day is recorded as taking place in April and was probably based on an ancient Roman festival that also honoured the dead and was held in May.

The Christian dates were shifted to October/November to combine them with a much older Celtic festival at that time of year which also involved the spirits of the dead.

It was common for Christian events to be linked with earlier pagan celebrations, as has also happened with Easter and Christmas.

So what are its origins?

We know from historical records that the Celts - whose tribes inhabited Britain during the Iron Age from around 800BC to the Roman Conquest - celebrated the festival of Samhain (pronounced sah-wen) from sunset on October 31 to sunset on November 1, halfway between the Autumn Equinox and Winter Solstice.

Celtic peoples in Scotland and Ireland, which did not become part of the Roman Empire, carried on such pagan traditions until the arrival of Christianity.

It’s thought that Samhain means summer’s end.

It was seen as the end of the harvest and the start of winter. Villagers brought the livestock back from the summer pastures and lit large fires for rituals.

People believed it was a time when the spirits of the dead were more easily able to return to our world.

These departed souls were thought to visit their former homes and so feasts were held to which they were invited for offerings of food and drink.

Members of the tribe dressed in costume, imitating the ancestral spirits, and went door to door reciting verses in exchange for food - clearly the origins of today’s trick-or-treating.

Appeasing the spirits with food meant the people and their livestock were given special protection so they survived the winter.

And these festivals are likely to have started even earlier - as far back as the end of the Stone Age.

A Neolithic burial mound in County Meath, Ireland, built between 3000BC and 2500BC, has a doorway that is aligned with the sunrise on October 31.

This suggests it was at that time that the dead were expected to return to the land of the living for a celebration of the end of summer and the start of winter.

So such events are likely to have their roots in the times when prehistoric man first became involved in growing crops and farming animals and used the sun as an agricultural calendar.